FLOOD10505

• County: Morgan
• Community: Brush
• Basin: South Platte
• Title: Brush - Storm Drainage Master Plan
• Date: 7/19/2006
• Prepared For: Brush
• Prepared By: Nolte Associates, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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I'JOlTE

City of Brush
Storm Drainage Master Plan

BeYOND ENGINEERING

retention ponds, additional alternatives were developed for 100-year, 24-hour storm
duration retention ponds for consideration of storage of larger, longer duration storms.
This additional alternative also provides more protection in the event of multiple storms
that occur in series.

Engineer's opinions of probable construction cost were developed for all alternatives
based on current 2006 costs. The construction cost opinions for each alternative were
derived by estimating the quantities for major work items required for each alternative
and multiplying by the unit costs (dollars per cubic yard, linear foot etc.). Quantities are
estimated from the master plan drawings prepared for each altemative. Unit costs for
each item were obtained from various sources including the Colorado Department of
Transportation, Urban Drainage and Flood Control District and experience with similar
projects. Work items included in the cost estimates include but aren't limited to storm
sewer, manholes, storm inlets, pavement removal and repair for trenches and excavation
or grading for retention or detention ponds. The total costs also include estimated
contingencies of25% and engineering costs of 10% of the estimated construction cost for
each alternative. Construction costs for each alternative for the 10-year and 25-year
storms are included in Appendix B of this report.

For the 100-year retention pond option, total costs are based on providing an increased
pond volume with storm sewer and other improvements based on the 25-year storm
(storm sewers are not typically designed to convey a 100-year design storm). Estimated
land acquisition costs are included for purchase of easements or drainage tracts at an
estimated cost of$15,OOO per acre. Costs are included for overlaying the entire street
width in areas of storm sewer or inlets. Overlay of the entire street is not always
necessary for a storm sewer project, but generally results in a longer effective pavement
life in the area of the construction.

Nolte Associates,Inc.

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